The following exercises are great to use in presenting a lasting image of the difference between observation and inference. In addition, other nature of science ideas emerge.
Time Required: 20 minutes
Source: Teaching about Evolution and the Nature of Science
This activity allows you to teach both observation vs. inference, and the idea that many things in science cannot be "proven," but must be inferred. It also reveals the impact of human perspective on science. For more details, see the link to the activity description.
Materials: Cardboard mailing tubes (you can also use toilet paper rolls, or even cereal boxes, but the mailing tubes are the most durable), rope, rubber bands, paper clips, key chain ring
Show students a model tube, with strings looped through a keychain, as seen above, or simply overlapping in the middle. When you pull on a string, it will pull out until the others are pulled tight to the knot. Ask students to make observations -- statements of knowledge gathered by their senses -- about the mystery tube. Then ask them to make inferences, or guesses, about what is happening inside the tube. Make the distinction between an observation and inference.
Student then have the chance to experiment. Ask them to write a hypothesis about what the ropes are doing inside the tube. Then give them an array of materials and ask them to recreate the model as best they can. Finally, ask students to show their models to the rest of the class. Likely, students will have different models that work as the original does. Make the point that in science, we often make models that explain the unseen, but we may not know for sure if they are correct. With technological advances, many of these "unknowns" are dispelled.
In the end, students will be itching to see what is inside your model. You may show them or decide not to... as long as they get the point of the activity!
Time Required: 15 minutes
Source: Teaching About Evolution and the Nature of Science
Link to Activity Description and Copy of Footprints
Materials: Overhead Projector, Transparency of Footprints
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Begin by revealing Position 1, at left on the overhead. Ask students to make observations, and then inferences about the picture and what may have occurred to create these marks. |
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Reveal Position 2, and ask the students to do the same- make observations and inferences. Have they changed their inferences? |
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Pictures From Teaching Evolution and the Nature of Science, National Academy Press, 1998
Finally, when the entire view is revealed, students may once again change their description of what they believed occurred here. You may receive some very creative responses!
Observations vs. Inferences. This is a good activity to use at the beginning of a unit on evolution. This activity is a fun way for students to see how observable evidence leads to conclusions in science, but that those conclusions can change when further evidence is presented. Also, many students in the class will have different explanations for what is happening in this picture. Discuss how the varied backgrounds and experiences of the students in the class affect their inferences.
Time: 20 minutes
Source: Original source unknown. I received the materials for this activity from Dr. Julie Westerlund, Southwest Texas State University.
Students cut out each dinosaur bone segment. The complete set of bones is shown below in three sets:
Dino Bones #1
Dino Bones #2
Dino Bones #3
Ask students to arrange the bones in the way that they believe the dinosaur existed. You will get many different arrangements! None of my students arranged the bones according to how the archaeologists arranged them, as seen below:
When you show the students the proposed skeleton of the Scaphognathus crassirostris, they will be amazed. Then, show them what archaeologists believe this extinct dinosaur once looked like with skin:
Discuss the implications. What type of evidence would have helped you put the bones together easier? What observations did you make about the different bones that helped you arrange them? What types of inferences did you make? Do you think archaeologists make similar inferences? How do they support these inferences? Where else do we see inferences in science?